Should I Put Water or Coolant in My Radiator?

What can I put in my radiator in an emergency? Should I put water or coolant in my radiator if it gets too hot? Here are all the answers.

Lowered levels of coolants can lead to overheating of your vehicle if you notice the higher levels on the temperature gauge in the middle of a ride with no nearby stores that have coolants, which leaves you in an emergency. 

In ideal conditions, you should always use a mix of coolant and water, in your vehicle’s radiator. Still, in emergencies when you don’t have access to coolant, you can put it in water. Read on below to learn more about using water or coolant in your radiator in case of an emergency.

Should I Put Water or Coolant in My Radiator

What Can You Put In Your Radiator?

In case of an emergency, when you are running low on a engine coolant overflow reservoir, or it is empty, and you are not near any shops that stock coolants, then you can put water in your vehicle’s radiator to cool it down. 

However, it is not a long-term solution. After putting the water in the radiator, ensure you don’t drive a long distance with that. Drive to the nearby stores or mechanic, flush the water off the radiator and refill it with the mixture of water and antifreeze in the right proportion.

Also read: What does foamy antifreeze mean?

Use Water In The Radiator Only In An Emergency

While driving, if you notice that the temperature gauge in your vehicle is showing higher readings, you should bring the vehicle to a complete halt as soon as possible. The higher levels of the temperature gauge are an indicator of engine overheating.

Allow your vehicle to cool down completely, and then check the level of the coolant overflow tanks. If the coolant level is low or the reservoir is empty, you need to refill it.

In ideal scenarios, you should put a coolant mix of water and antifreeze in the ratio of 50/50, but if you are in the middle of nowhere and have to keep driving, then you can put cold water in the radiator.

To put water in the radiator safely, you need to follow these steps:

  • Bring your car to a complete halt, shut off the engine and put your vehicle in neutral, or park and apply the parking brakes.
  • Once the engine is cooled down, remove the cap on the coolant reservoir. 
  • Unscrew the reservoir cap using a cloth or towel, let the pressure release, and then remove the cap.
  • Use soft, distilled, or purified water to fill the radiator up to the fill line, then shut the reservoir cap back.

While not an ideal solution, using water is still better than driving with low or no fluid at all.

Should I Put Water or Coolant in My Radiator

Pros and Cons of Using Water

A coolant increases the boiling point, lowers the freezing point of water, and is also responsible for preventing corrosion in the cooling system. Using water in place of coolant contaminates the cooling system. 

While in case of an emergency, it is better to drive with water in the radiator rather than low or coolant, you can drive your vehicle for a very short distance using this method. 

Get the water replaced with coolant as soon as possible, as water won’t offer any protection to your motor. Getting to the reason for the lower coolant level is important, and getting it fixed is essential.

When To Add Coolant To The Radiator Again?

Once you have put water in the radiator, drive your vehicle over to experts as soon as you can and get it checked. 

The mechanic will determine the reason for the low or empty coolant overflow reservoir, replace worn-out parts, and repair the leaks if any. 

Once it is done, the mechanic will flush the radiator and refill it with a 50/50 mixture of antifreeze and water. Fusing the radiator before refilling is essential, and failure to do so can result in the radiator failing.

What Will Happen If You Use Water Instead of Coolant?

In most cases, when there is an emergency, it is okay to use water instead of coolants. However, water has a lower boiling point than antifreeze and does not offer any protection from freezing. 

You should only use water as a temporary solution and replace it with the correct coolant as soon as possible. Using water instead of coolant for a longer period can result in corrosion. 

Also, the water doesn’t offer any freeze protection, which means if it freezes, it can result in cracks in the cylinder head and engine blocks.

Should I Put Water or Coolant in My Radiator

Does the Type of Water Matter?

While any type of water is not safe for long-term use in the cooling system of a vehicle, some types of water can lead to corrosion and scale build-up inside the coolant system. 

Tap water contains minerals that can build up corrosion inside the cooling system. That is why, in case of an emergency, a few types are more favorable than others.

Types of water that are safe to use:

  • Soft water
  • Purified water
  • Distilled water

Types of water that are not safe to use:

  • Spring water
  • Ordinary tap water

Ways to Avoid Overheating

There are a few ways you can avoid overheating your vehicle.

  • Some vehicle models overheat more than others due to a design fault or other reasons. Check if your vehicle has a warranty or service, as the repair may fix the issue.
  • Keep an eye on the temperature gauge while driving. If the reading remains stable under all driving conditions, the engine cooling system works fine. If the reading shows higher levels, then there might be some cooling system issue that you need to repair right away.
  • Look out for leaks in the coolant overflow reservoir. If you find a coolant puddle beneath your vehicle, then there is a leak that you need to repair. Once done, refill the reservoir to the optimum level.
  • Check all the belts and hoses and replace any worn-out or damaged parts.
  • When refilling the coolant reservoir, ensure you use the right proportion of antifreeze and water mixture. It should be between 40:60 and 50:50.
  • Overloading your vehicle can also lead to overheating. Never go over the weight limits suggested by the manufacturer of your vehicle.
  • Check the brakes on your vehicle, and if they are not working properly, they can cause overheating of your vehicle.
  • Routine maintenance of your vehicle is the best way to avoid overheating or any other serious problem in your vehicle.

Should I Put Water or Coolant in My Radiator

Wrap Up

You should always put a coolant mixture in your vehicle’s radiator, but there are unavoidable scenarios when you don’t have coolants and your vehicle is overheating. In such cases, you have to put water in the radiator. Thank you for reading the article. We hope you were able to find what you were looking for.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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